PURPOSE: To easily remove joined long size materials by providing a couple of clamps to hold two base metals on the same axial center and a chuck to hold a short size piece and rotate on the same axial center as the metals between both clamps and forming attaching and detaching grooves on the clamps and chuck.

CONSTITUTION: The base metals 2A and 2B arranged at an interval where the short size piece 7 can be inserted are held by the clamps 3A and 3B via the attaching and detaching grooves and the short size piece 7 is inserted from the attaching and detaching groove 12a of the chuck 8 and held by the chuck 8. The chuck 8 is then rotated at high speed via two intermediate gears 16A and 16B and the end faces of the short size piece 7 and the base metals 2A and 2B are pressurized via the clamps 3A and 3B by jacks 6A and 6B and the pressurized faces are heated by frictional heat. When the pressurizing temperature is attained, the chuck 8 is then stopped and at the same time, the pressurizing force is increased by the jacks 6A and 6B and joining is carried out. The joined long size materials are then removed from the attaching and detaching grooves of the chuck 8 and the clamps 3A and 3B.